Manufacture of metal products



sept. 2z, 1942.

H. A'. BRASSERT MANUFACTURE OF METAL PRODUCTS Filed March 9, 1940Patented Sept. 22, 1942 MANUFACTURE F METAL PRODUCTS Herman A. Brassert,New York, N. Y., assignor to Mine rais and Metals Corporation, New York,

N. Y., a corporation of Delaware Application March 9, 1949, Serial No.323,076

(Cl. 'i5-9i) 2 Claims.

This invention relates to the direct reduction of iron and othermetallic ores and the production of metal products from the reducedmetal` in a continuous process without involving a melting step.

The production of metals such as iron directly from the ores without amelting step is well known and has been accomplished by severalprocesses. These prior processes enable ybut a low rate of production,either because of the slowness of the reduction process itself, orbecause of the limited production capacity of the reducing furnaces or:other reaction equipment, or both. Accordingly, unless the reductionequipment is materially multiplied or increased to a sizedisproportionate to the output, these prior direct reduction processescan not cornpete with the conventional smelting process of producingmolten metal in suicient volume to 'continuously and economically feedmodern steel mills. The smelting process, for instance in blastfurnaces, is relatively expensive and because un-` desirable elementsare avidly absorbed from coke and uxes by the metal in its molten state,the resulting product is impure and a purifying step before iinishing isgenerally required in order to eliminate, neutralize, or minimize theimpurities. But the smelting process, although objectionable for thereasons mentioned, is today the only' practical process of producingmetals from ores in sufficient quantity to render their proin manylocalities, to the end that a metallic product is obtained which maycompete,`in so fa;` as quality and purity are concerned, with the iron,steel, and other metals produced in the open hearth and electric furnaceor by the vcrucible process, and at much lower cost.

A further object of this invention is to produce semi-finished andfinished metal products having a controlled grain structure and otherselected physical andchemical properties corn-` mensurate with the'intended use of theproduct.

These and other objects of theinventionlare obtained by grinding theore, such as iron ore, or roll scale, or other metal oxides, to apulverulent state, preferably down to mesh or ner; substantiallyentirely removing the gangue therefrom by magnetic or electrostaticseparation, flotation, jigging, or chemical or other methods ofconcentration; adding to the pulverulent ore such fluxes, alloyingmetals 6r other modifying agents as may be desired, or reducing agents,these agents being likewise pulverulent; passing a reducing gas througha mass of the ore or continuously through a ,stream of the ore forleffecting the reduction thereof while heated to the reducingtemperature, but without fusion; agitating the ore while it is beingtreated with the reducing gas to accelerate the reducing reaction, andthen discharging the redu d ore, preferably while still hot or furtherhea d to a grain-consolidating temperature, to a suitable compacting anddeforming apparatus. such as an extrusion press, rolling mill, forge, orthe like, for Working the heatedlreduced particles into la solidhomogeneous product which may then be further worked to convert it intoa semifinished or nished product.

In a preferred embodiment of the apparatus of `thls`invention, thepulverulent raw ore, with or without modifying or reducing )agentsadmixedA therewith as described, is advanced along a perfor-ate orpervious deck while being heated to the reducing temperature, and areducing gas is forced through the perforations or interstices in the'deck so as to pass through and mix tintimately with the ore and thusreactwith the of the spent gas envelopes surrounding the particles, thuspermitting fresh reagent to attack the unreduced Iportions of the ore inthe particles under the reduced surfaces thereof.

In'one form of the apparatus, this agitation` of thenfore particles iseffectedk by vibrating the deck in such a way that the particles areprojected upwardly and vforwardly as in a `r`conventional vibratingconveyor, so that the ore is advanced through the' reducing zone. whilebeing gradually reduced to metal. This action is carried on for asuflicient time and/or length of conveyor until completely reduced andis then discharged by the vibrating deck intov a further heating zone ordirectly to the apparatus for compacting the particles into a bloom,billet,

l or thelike. v

It will be seen thatby means of this invention, pure metal productshaving superior physical and chemical properties can be producedeconom-- ically and efficiently directly'from the orewithout requiringan intermediate meltingstep. Bej cause there is no melting step theabsorption of undesirable elements is precluded, since the metallicpowder does not come into contact with impurities, such as carbon,sulphur, phosphorous,

and other detrimental materials contained in the coke as loccurs in theblast furnace. Also, the physical and chemical properties of thefinished or semi-finished materials may be' closely con,-v

trolled inthe'process and apparatus of this ing vention by the particlesize, the temperature and x by admixing of proper modifying or reducingagents. These advantages are obtained without loss of materials and thereagent gas is readily available in many localities having natural or`articial gas, such. as by-product gas, water gas, rened oilr gascontaining the proper reagent ingredients, such as carbon monoxide,hydrogen, or hydrocarbon compounds, or organic compounds, or mixturesthereof.

the process of extruding, rolling. or forging, such fluxes having asubstantially lower melting point than the metals and beingsubstantiallyas flnelyi divided as the ore powder, or finer;` orsilicon, carbon, sulphur, or other elements desired in the finishedsteelmay be added in powdered form to the rawy ore powder; or manganese,titanium, nickel, chromium, or other metals or alloys of such metalswith iron or withl each other, or reducible components thereof, in theform of powder, preferably as rie -as the ore powder, o'r y finer, maybe admixed with the raw ore powder for the production of alloy steels.In some cases,

' additional reagent, such as reducible compounds ,'sary.

For a more completev understanding of the invention, reference may behadto the accomvpanyirig drawing, in which:

Figure l is a diagrammatic representation of one form of the apparatusfor conducting the process of this invention, and i like ferro-silicon,pure carbon, such ascarbon black, ground pitch, substantially ashandsulphur-free coal or charcoal, may be addedin order to facilitate thereducingreaction, but in most instances Where the proper reducing gas isobtainable this additional carbon may not be neces- Referring'to Fig.-l, numeral I0 designates a vibrating feeder comprising a hopper I Icontaining the pulverulent rawore, this hopper II Adis--` charging uponan elongated Vtray or pan- I2 supported on spaced spring bars I3anchored at their llower ends on a,suitable base I4, which also rigidlysupports vibrator I5, preferably of the electric type, for vibrating thehopper II and the tray I`2 at `high frequency, the tray being vibratedin a generally lengthwise direction, i. e., in the general direction-oftravel desired for the material. rThe frequency of the vibration for thefine material here employed depends on the loady and rate `of Fig.l 2 isa transverse section through the ref ducing chamber as seen along theline 2-2 of Fig. l1. y' l An example of the material to be treated 'ispreferably a rich iron ore, such as magnetite or hematite, although itmay be a non-ferrous ore,

or mixtures thereof, depending upon requirements. and then pulverized,as by grinding to a fineness such that the valuable portion ofthe oremay be readily freed from the gangue, which is associatedtherewith.Depending upon the nature of the' ore, the degree of lpulverization maybe quite fine, for instance.:I such that it will pass a 60 'to 100 meshscreen. If higher grade products are required, or the 'ore containsconsiderable gangue. or lgangue diiiicult to remove, the ore fmust beground stilll finer, such a's up to 200 or even up to 400 mesh size.lfOn the other hand, the ores may be of such porosity as to bevpermeableto thereducing-agent and thus donot require such fine grinding.'I'liegangue isv then separated from the remainder of the ,ore in` anysuitable way,

such as by magnetic or`electrostatic separation ,y for magnetite ore,:ligging or flotation for hema-1,

tite and other non-magnetic ores, chemical, or

other methods of -b'eneficiatiom If the raw material is in the form ofiron sands or roll scale, it

may be concentrated, if necessary, in these or The ore, for example,iron ore, is crushed other ways directly without the crushing step, al-I though fine grinding to the required pulverulent Astate is even thennecessary in most instances.

The pulverulent raw ore mayA have admixed therewith', ifVv desired,certain modifying :,agents,

such as soda,fluorspar, or other uxes for the purpose of combiningwitlithe remnant of impurities left inthe powder to be'squ'eezed out inv75v feed. Thus, by adjusting the unit .number of v vibrationsimpartedtothe tray I2, the rate and volume of feed cf the material along tray I2may be regulated with great accuracy. The particular type of vibratorfeeding impulse mechanism shown herein formano part of the presentinven-t tion, but is a commercial vibratory feeder, further details ofwhich may be obtained upon reference' to Patent No.'2,094,787, issuedOctober 5, 1937, to J. G. Flint. Equivalent vibrating feeding mechanismmay bev used with equal facility.

If the aforementioned modifying agents, fluxes,

reagents, or the like, arev to be agmixed with the 'ore powder, thevibrating conveyor I0 Whose rate of feed is lniown,.dischargesy into asuitable me'-A chanical mixer I6 whose motor-driven beater, not shown,mixes with the ore powder a predetermined` proportion of the modifyingor reducing agent, flux, or mixtures thereof, which are introduced intothe mixer by means of a hopperv I1. If desired, a vibrating feeder like@I0 .may be utilizedy to supply a continuous stream .of the modifying orlreducingagent or flux, into the mixer IB in. theproper unit volumeratio to the ore powder supplied to the mixer by feeder I0.

Whether or not the mixer isv used, the finelydivided material isdischarged through spout I8` directly into the retort I9, which, asshown particularly in Fig. 2, is preferably a rectangular section tube20 suitably covered with ka. layer of heat-insulating material, with theexception of its bottom wall. The entire retort I9 may bethrough thesepassages.

fractory material, such as silicon carbide, known` commercially ascarborundum, which' is naturally pervious, or aluminum oxide,known-commercially as alundum, or other similar material, made perviousby being so prepared as to contain a myriad of closely spaced very nepassages extending from its bottom surface therethrough to the topsurface thereof, so that communication between the chambers 23 and 22 isprovided 'I'he deck 2| is preferably tapered, as seen in Fig. 1, thusproviding a gradually increasing cross-section of hearth and a graduallydecreasing cross-section of gas chamber 23, the purpose of which will bedescribed.

.The retort I9 is preferably supported by ilexible bars 24 on the base25 and is vibrated at high frequency by vibrator 26, `which is. likevibrator I previously described. so that the retort I9 acts as aconveyor of the powdered material in the manner described in saidpatent. Accordingly, the raw ore discharged'by spout I9 on the deck 2|is advanced therealong in a continuous stream from left to right, asseen in Fig. l.

Directly connected to reagent gas chamber 23 is a gas supply pipe 21through which reagent gas is supplied to chamber 23 by a pump 28 drivenby an electric motor 29 or other power source. The gas is drawn by pump29 from a gas supply main Y3|! through pipev 3|. In order to accommodatethe vibration of the retort I9, the connection between gas pipe 21 andchamber 23 is effected throughy a flexible coupling 33. v The pressureatwhich the reagent gas is continuously supplied to chamber 23 issuilicient .to enable -the gas to ow upwardly through the pervious bed2l and percolate through the vibrating and advancing ore bed 32 undersuiilcient pressure to completely envelop each ore particle and aid increating the desired turbulence in the ore.

In order to preclude cracking of the gas in the pores of the deck 2| atthe temperature of reduction of the ore, and consequent clogging of thepores by deposited carbon, tars and the like, a gas is selected whichdoes not crack or otherwise deposit solids at the working temperature ofthe retort, or which has a higher cracking temperature, or the gas maybe cracked or otherwise .treated to remove or x these materials beforeuse in retort I9.

Positioned beneaththe floor of chamber 23 is a series of gas burners 34supplied by a manifold 35 in turn supplied by gas main 3l! under asufficient pressure to insure steady supply for` combustion intheburners 36. The burners '3d are positioned immediately beneath the floorof the gas chamber '23 so as to heat the gas toy the proper temperaturefor effecting reduction of the ore in the manner to be described.

Connected to spaced points along the retort I9 and discharging intoreducing chamber 22 are a plurality of pressure air pipes 36 controlledby valves 31 for bleeding in suiiicient pressure air 'from supply 39 toburn the excess reducing gas end of the retort I9 as seen in Fig. 1, andserve to pre-heat the ore as it discharges from spout I3. These gasesare withdrawn through duct 39 by a suction pump 49 driven from motor 29after the gases have passed through a heat-exchanger 4| surrounding gassupply pipe 21, whereby the reduction gas is conveniently preheated. Thespent products of combustion may be discharged to a stack 42 by suctionpump 40.

In order to more readily start the reducing operation and accelerate itafter starting, the ore may be preheated by bleeding a small quantity ofthe combustible reducinggas from chamber 23 through small openings inthe iloor 43 ahead oi' the deck 2|. This gas percolates through the oredeposited on oor 43 from chute I5 and mixes with the air entrainedtherein, although additional air may be supplied by pipe 36. Uponignition of this gas-air mixture within the ore the oxygen in theentrained air is not only removed, butthe ore is preheated. fCommunicating with the discharge end of retort I9 through a chute 44 isa muille 45 arranged in the fo'rm of another enclosed vibratory conveyorsimilar to retort A|9.except that the perforate deck 2| is omitted., Thematerial is advanced over the imperforate deck 46 in' the mannerdescribed in said patent, the vibratory impulses being supplied byvibrator 41 Which is like vibrators I5 and 25. 'I'he deck 46 issupported by flexible bars on base 25 and is enclosed by a hood 49. Gasburners 50 p sitioned immediately below deck 49 heat the re ucedmaterial to` they temperature necessary to consolidate the-particles,which is usually near welding temperature but short of actual fusion toprecludepsticking of the particles to the walls of the` apparatus.

'I'he vibratory mulile 45 discharges into a stationary vertical hopper5| ofsquare cross-section sealed to the end of the muiiie 45 by ailexible collar which accommodates the vibration between them. 'I'hehopper 5| contains a reciprocating plunger 52 driven byair cylinder 53for initially compressing the reduced ore powder in cylinder 54 ofextrusion-press 55. Cylinder 54 of press 55 is of square cross-sectionand contains the reciprocating plunger 55 driven by the vhydraulic ram51. Cylinder 54 communicates with a converging extrusion die 58 oppositethe end of plunger 56 and in turn discharging on to a roll conveyor 59.Hopper 5| may be heated if desired, so asv to maintain the material hotin its course to the cylinder 540i press 55, which may be likewiseheated if. desired, but ordinarily neither hopper nor press need bespecially heated.'

ner described, is supplied from hopper by vibrator feeder t@ to themechanical mixer I6, in which the aforementioned fluxes, alloyingmaterials, or other modifying agents, or reducing agents,continuouslyadded by hopper l1 in proper ratio to the raw ore, areadmixed therewith. Whether or not these additional materials are added,the raw ore is discharged by spout I8 upon floor 43 for preheating bycombustion of gas therein. The preheated ore is advanced from iioor 43to deck 2| and therealong bythe high frequency vibration impartedthereto and to the of these gases are withdrawn from the left-handentire retort I9 by one or more of'the vibrators 29 in the manner`described in said patent. In this way, the raw ore israpidly agitatedand simultaneously gradually advanced along the deck '2l with thecontinuous up and down and simultaneous vforward progressionlrnotionjcharacteristic of that method of vibration.

Asfthe mass of raw ore in this state of continuous vibration is advancedalong deck 2l, the

reducing gas is/forced through the interstices in.the deck 2| so as topenetrate the ore bed 32 andV percolate therethrough in a myriad of.fine l streams in intimate contact with each vof the vi- 'theinterstices therein are longer and thus in- Y crease friction to reduceultimate gas pressure.

In order to supply ample reducing gas to enthe water vapor and toconvert carbon dioxide to lbr'ating ore particles. 'I'his gas is heatedto such temperature that the ore is treated at its reducing temperature,Which is .in the neighborhood 1 'of 1800 F. for relativelypure'magnetite.-

vAll of the heat need not be supplied by the sensible heat of thereducing gas or the burning i gas in the ore on deck 43, inasmuch as thesurvapor and the carbon dioxide.

plus gas notl required for the-r reaction that emerges from the bed L32and `the combustible products of the reactionare burned within thereducing chamber 23 above the bed` by adding i a suiiicient amount ofair thereto through pipes 36 in the manner described. In any event, theore is, uniformly heated to the reducing temperature andthe reactiontakes place in the 1 'known manner, the oxidesof the ore combining lwith the reagent, whether gaseous or gaseous and solid, thusleaving'substantially pure metal. For example, for iron oxide, thereducing gas may be feither hydrogen or carbon monoxide or mixtures Ithereof, or a gas-plus a, solid reagent like'carbon l admixed with theore. Preferably a natural gas i rich in hydrogen or carbon monoxide orboth, j or articial gases, such as by-prduct gas, -water gas, refinedoil gas containing the proper reagent ingredients, or properlyconstituted. hydrocar- 1 bon compounds, or organiccompoundsor mixl turesthereof, for example. Preferably the remducing gas should contain nodeleterious subi stances such as sulphur or sulphur-forming f compounds,although inasmuch as the material is not molten, sulphur and the likeare not readg ily absorbed thereby, so that sulphurous materials, suchas sulphur-containing solid reagents l [may be used without detrimentaleffects.

During the reaction the particles of ore are in r constant motion, dueto the high frequency vi,

l bration imparted thereto by the vibrator 26 in working the ore bed 32along. the dck 2l, as de- .scribed, which is aided'by` the gaspercolating therethrough under pressure. This turbulent vibrating-motion has the effect of continuously loosening and moving the compactparticles relcarbon monoxide,` or the recirculating gas may be purifiedas by washing to'remove excess water Electric arc regenerationy or otherregeneratingyor purifying' processes may be employed.

It will be understood that the retort I9-may be aslong Vas requiredcommensurate with therate of reduction on which depends the rate ofprogression of the .ore and degree of heat application thereto. Theheating is progressive so that the reaction progresses gradually andresuits in a more complete reduction than if the reaction were promotedsuddenly in a short heat zone. Thus, -with a properly vadjusted rate offeed, length of retort I9, and heating degree the material `reaches theend of the retort I9 as completely reduced ore. This reduced oredischarges into the muille 45 through which it is advanced by thevibratory motion imparted by vibrator 41 l while being heatedto a high1temperature, al-

though less than fusion, to be discharged into chute 5I to be compactedin cylinder 54 by reciprocating plunger 52 which is synchronized withpress plunger 54 so that the latter remains retracted to expose theinterior of cylinder 54 while the plunger 52 forces the`material-there 1in. The compacted hot .material in cylinder`54` is then forced byplunger 56 through converging extrusion die 58 to be compacted in alldirections laterally and longitudinally into af denseA homogeneous bloomor billet B.

Binet 1av is preferably of relatively large dif mensions comparable tothe blooms or billets fed to the metal working equipment of a. modernsteel mill, such as rolls, hammers, forges, presses,

atively'to each other with a rubbing or attritionV action, which notonly results in removalpf the :reduced metal skin on veach p a'rticlebut also repeated rupture of' the envelope of spent gases `surroundingeachparticle, thus enabling the con- `stantly Acirculating fresh reagentto attack the unreduc'ed portions of the particles. Thisatso that evenrelatively initially large particles ,that are porous to the'reagent aremore finely-.- "divided as they progress through the retort, so

`that they emerge as a smaller mesh size. r The ore volumeis decreasedduring reduction.

`-allo'ying metals, or the like.

.further'extrusion or drawing dies, tube mills,-

ring or push benches, and the like. Before'being fed to such finishingor semi-finishing 'equipmentthe bloom, or .billetB may be reheated ifdesired, or it may be cold finished.

The billet B, when extruded as described, has

transverse `tensile strength equivalent to its lon-l y gitudinal tensilestrength, and has `a very'flne grain structure, modified as andifdesired by the inclusion of the aforementioned elements, vWhile thedirect Vextrusion of the finely-divided reduced ore in the mannerdescribed is preferred, the reduced ore 6dmay be `compacted into aself-contained billet, trition gradually reduces the size oftheparticles which is then heated to or near the welding tem- 1 perature ofthe material and worked into a ho- -mogeneous metal body, as describedin cepending application Serial No. 316,717, led February 1,@1940, by H.A, Brassert; orthe reduced ore powder may be charged into containers ofsimi` lar metal, the whole heated to the consolidation temperatureand-the container and its contents worked into a. unitary body, asdisclosed in coruary 14, 1940, by H. A. Brassert.

pending application Serial No. 318

,814, filed- Feb- 1 T he various Asteps in the process from thereducmgzone to the press 55 are conducted under -neutral atmospheric conditions'to preclude reoxidation of the reduced ore. y The gaseous prodsuctionpump drawing the spent and surplus reducing gas downwardly through theore bed and pervious vibrating deck 2|. The heating may be effectedjointly by burners 34, or burning the surplus combustible gas in chamber23, or burning some ofthe reducing gas in reducing charnber 22, orcombinations of these means.

Although the deck 2l vis shown horizontally arranged, it may be tilteddownwardly or upwardly from the intake end, depending upon requirements,this tilting having an eiect on rate of feed, gas flow, and the like.

Instead of heating the pulverulent material either in the raw or reducedstate by external heating means, such as th'e gas burners 34 described,the material may be heated in other known ways, such as by electricresistance heaters within the mass of 'the charge, burners within theretorts I9 or the Inutile 45, or by electric induction in a mannersimilar to that described in copending application Serial No. 319,197,filed February 16, i940, by H. A. Brassart.

Also,I by heating the reduced material in th'e press 55 to the plasticstate, such as by the-electric induction method described, or otherheating method, the material can be immediately worked ,into finishedshapes, rails, and the like, by providing` an extrusion die 58 with theproper conguration, thus' eliminating the first particle consolidationstep and going directly to th'e metal shaping step. Conversely, thematerial may be discharged directly from the retort i9 to the extrusionpress 55 for compacting into a bloom or billet requiring further workinginstead of being rst heated to a higher temperature in the muiTle 45.

From the foregoing description "of a typical embodiment of theinvention, it will be apparent that this invention provides very simpleand effective ways of rapidly and continuously and directly convertingpulverulent raw ore into solid, dense and homogeneous bodies easilyconverted into 5 treatment of iron and steel, it is also possible totreat other ferrous or non-ferrousmetals or alloys in a similar way.Therefore, the above-described example of atypical embodiment of th'eprocess should be considered as illustrative only and not as limitingthe scope of the following claims.

I claim: y 1. The process of making a metallic product, which comprisescharging pulverulent raw ore into a closed retort, vibrating the ore athigh frequency while in said retort in such manner as to eiect bothagitation and an advancing movement thereof, simultaneously passing areducing gas upwardly through the independently agitated charge in agreat number of closely spaced individual streams distributed throughoutthe mass of ore, heating the mixture while so treated with gas andvibrated to effect reduction of the raw ore, admitting a suiicientamount of oxygen tothe retort above the charge to sustain combustion ofthe combustible products of the reaction, dis'- eharging the reduced orefrom the retort and continuously withdrawing th'e gaseous products oithe reduction and combustion in 'counterfiow relation to the movement ofthe ore through the retort. i

2. The process of making a metallic product, which consists inestablishing and maintaining a layer of powdered ore to be reduced ofsubstantially uniform depth in any section transverse to its directionof travel, subjecting said layer of powdered ore to the percolatingaction of a reducing gas directed upwardly against the bottom side cfsaid layer in jets immediately adjacent to each other and so distributedthroughout the entire bottom area of said layer as to subjectsubstantially the entire under surface of saidlayerto immediateimpingement thereby, independently -agitating the ore to facilitatebothpercolation o! the reducing gas through the layer of powdered ore,reactive contact of all particles of the ore with said gas and travel ofthe powdered material through the reaction zone, simultaneously heatingthe powdered ore to a reducing temperature semi-finished or finishedmetal products, such as shapes, rails, tubes, sheets, and the likeVandthat while the process is particularly applicable to the lessthan thefusion temperature of any ofthe constituents thereof, at least a part ofsaid heat being provided by supplying substantially only

